Its phonation is voiceless, which means it is produced without vibrations of the vocal cords. In some languages the vocal cords are actively separated, so it is always voiceless; in others the cords are lax, so that it may take on the voicing of adjacent sounds.

It is an oral consonant, which means air is allowed to escape through the mouth only.

It is a central consonant, which means it is produced by directing the airstream along the center of the tongue, rather than to the sides.

Varieties

Occurrence

The voiceless velar fricative and its labialized variety are traditionally postulated to have occurred in Proto-Germanic, the ancestor of the Germanic languages, as the reflex of the Proto-Indo-European voiceless palatal and velar stops and the labialized voiceless velar stop. Thus Proto-Indo-European *ḱr̥nom "horn" and *kʷód "what" became Proto-Germanic *hurnan and *hwat, where *h and *hw were likely to be [x] and [xʷ]. This sound change is part of Grimm's law.

In Modern Greek, the voiceless velar fricative (with its allophone the voiceless palatal fricative [ç], occurring before front vowels) originated from the Ancient Greek voiceless aspirated stop /kʰ/ in a sound change that lenited Greek aspirated stops into fricatives.